1. Field of the Invention
The present invention relates to control of an electrophotographic printer having a non-volatile memory inside the printer or in a functional portion capable of transmitting and receiving data to and from the main body of the printer and detachably attachable to the main body.
2. Related Art
FIG. 9 is a block diagram showing a configuration of a conventional printer control portion.
Numeral 101 designates a printer controller, which executes communication with a host computer, which receives image data to expand the received image data into information for the printer to be able to print, and which executes exchange and serial communication of signals with a printer engine control portion described hereinafter. Numeral 102 is an engine control portion, which executes control of each unit in a printer engine through the exchange and serial communication of signals with the printer controller.
Numeral 103 denotes a sheet convey control portion which feeds and conveys a sheet to be printed and which executes sheet conveyance up to discharging of a sheet after being printed, based on an instruction from the engine control portion; numeral 104 an optical system control portion which executes control to drive a scanner motor and ON/OFF of a laser, based on an instruction from the engine control portion; numeral 105 a high voltage control portion which executes output of high voltages necessary for the electrophotographic process including charging, developing, transferring, and so on, based on an instruction from the engine control portion; numeral 106 a fixing temperature control portion which performs control of temperature of a fixing device, based on an instruction from the engine control portion, and which performs detection of abnormality of the fixing device, and the like; numeral 107 a sheet presence/absence sensor input portion which transmits information of sheet presence/absence sensors in a sheet feed portion and in a sheet conveyance path to the engine control portion; numeral 108 a jam detecting portion which detects defective conveyance during sheet conveyance; numeral 109 a breakdown detecting portion which detects a breakdown of a functional part in the printer; and numeral 110 a toner cartridge detachably attachable to the printer engine.
A non-volatile memory 111 capable of transmitting and receiving data to and from the engine control portion is mounted in this toner cartridge, thereby constituting a configuration enabling reading of data from the engine control portion or writing of data therein.
Conventionally, the engine control portion was configured to count up in the non-volatile memory, data concerning consumption of consumable supplies in the process cartridge, e.g., data about operation of the drum (time of rotation of the drum or the like), the residual amount of toner, etc., and to perform, upon arrival at a predetermined threshold, such control as to inform the printer controller of the fact.
The conventional apparatus was, however, designed without sufficient consideration to timing of carrying out a switch process of primary current values for lengthening the lifetime of the process cartridge and thus had the problem that switching occurred during execution of the electrophotographic process, so as to fail to maintain the uniformity of image quality.